Lise Nistrup Jørgensen

Fusarium Head Blight of Cereals in Denmark: Species Complex and Related Mycotoxins

Quantitative real-time polymerase chain reaction differentiating 10 Fusarium spp. and Microdochium nivale or M. majus was applied to a total of 396 grain samples of wheat, barley, triticale, oat, and rye sampled across Denmark from 2003 to 2007, along with selected samples of wheat and barley from 1957 to 2000, to determine incidence and abundance of individual Fusarium spp. The mycotoxins deoxynivalenol (DON), nivalenol, zearalenone, T-2, and HT-2 were quantified using liquid chromatography-double mass spectrometry. Major differences in the Fusarium species complex among the five cereals as well as great yearly variation were seen. Fusarium graminearum, F. culmorum, and F. avenaceum were dominant in wheat, with DON as the dominant mycotoxin. F. langsethiae, F. culmorum, and F. avenaceum were dominant in barley and oat, leading to relatively high levels of the mycotoxins T-2 and HT-2. F. graminearum, F. culmorum, and F. avenaceum dominated in triticale and rye. The nontoxigenic M. nivale/majus were present in significant amounts in all cereal species. Wheat and barley samples from 1957 to 1996 exhibited no or very low amounts of F. graminearum, indicating a recent increase of this pathogen. Biomass and mycotoxin data exhibited good correlations between Fusarium spp. and their corresponding mycotoxins under field conditions.

IPM Strategies and Their Dilemmas Including an Introduction to www. eurowheat.org

Information about disease management in winter wheat (Triticum aestiva) in eight European countries was collated and analysed by scientists and extension workers within the European Network for the Durable Exploitation of Crop Protection Strategies (ENDURE). This included information about specific disease thresholds, decision support systems, host varieties, disease prevalence and pathogen virulence. Major differences in disease prevalence and economic importance were observed. Septoria tritici blotch (Mycosphaerella graminicola) was recognized as the most yield reducing disease in countries with intensive wheat production, but also rust diseases (Puccinia striiformis and Puccinia triticina), powdery mildew (Blumeria graminis) and Fusarium head blight (Fusarium spp.) were seen as serious disease problems. Examples of current integrated pest management (IPM) strategies in different countries have been reported. Disease management and fungicide use patterns showed major differences, with an average input equivalent to 2.3 full dose rates (TFI) in the UK and a TFI of 0.6 in Denmark. These differences are most likely due to a combination of different cropping systems, climatic differences, disease prevalence, and socio-economic factors. The web based information platform www.eurowheat.org was used for dissemination of information and results including information on control thresholds, cultural practices which can influence disease attack, fungicide efficacy, fungicide resistance, and pathogen virulence, which are all elements supporting IPM for disease control in wheat. The platform is open to all users. The target groups of Euro Wheat information are researchers, advisors, breeders, and similar partners dealing with disease management in wheat.

Investigation of the effect of nitrogen on severity of Fusarium Head Blight in barley

The effect of nitrogen on Fusarium Head Blight (FHB) in a susceptible barley cultivar was investigated using gel-based proteomics. Barley grown with either 15 or 100kgha(-1)N fertilizer was inoculated with Fusarium graminearum (Fg). The storage protein fraction did not change significantly in response either to N level or Fg, whereas eighty protein spots in the water-soluble albumin fraction increased and 108 spots decreased more than two-fold in intensity in response to Fg. Spots with greater intensity in infected plants contained fungal proteins (9 spots) and proteolytic fragments of plant proteins (65 spots). Identified fungal proteins included two superoxide dismutases, L-xylulose reductase in two spots, peptidyl prolyl cis-trans isomerase and triosephosphate isomerase, and proteins of unknown function. Spots decreasing in intensity in response to Fg contained plant proteins possibly degraded by fungal proteases. Greater spot volume changes occurred in response to Fg in plants grown with low nitrogen, although proteomes of uninfected plants were similar for both treatments. Correlation of proteome changes with measurement of Fusarium-damaged kernels, fungal biomass and mycotoxin levels indicated that increased Fusarium infection occurred in barley with low N and suggests control of N fertilization as a possible way to minimise FHB in barley.

TRI12 based quantitative real-time PCR assays reveal the distribution of trichothecene genotypes of F. graminearum and F. culmorum isolates in Danish small grain cereals.

Quantitative real-time PCR assays, based on polymorphisms in the TRI12 gene of the trichothecene pathway, were developed to identify and quantify the trichothecene genotypes producing 3-acetyl-deoxynivalenol (3ADON), 15-acetyl-deoxynivalenol (15ADON) or nivalenol (NIV) in the Fusarium graminearum species complex, Fusarium culmorum, Fusarium cerealis and Fusarium pseudograminearum. These assays were applied on a total of 378 field samples of cereal grain of wheat, barley, triticale, rye and oats collected from 2003 to 2007 to study the trichothecene genotype composition in Danish cereals. The three genotypes, 3ADON, 15ADON and NIV were found in all five cereal species, great annual variation in the occurrence of the trichothecene genotypes was evident with considerable variation between the samples. 3ADON was the dominant genotype in barley, triticale, rye and oats while 15ADON was most dominant in wheat. The NIV genotype was found at low levels in most samples. Study of genotype composition within the Danish F. graminearum and F. culmorum population was based on principal component analysis (PCA). PCA revealed that the dominating genotype of F. graminearum in wheat is 15ADON. For barley, the PCA analysis indicated that the F. graminearum population consisted of all three genotypes, and in triticale, the F. graminearum population consisted mainly of 15ADON genotype. F. culmorum/F. cerealis showed correlation to the NIV genotype in wheat and triticale but not in barley. F. culmorum/F. cerealis also showed some correlation to 3ADON especially in wheat and triticale. Selected wheat and barley samples from 1957 to 2000 showed low amounts of F. graminearum and F. culmorum in general but with a dominance of the 3ADON genotype. 15ADON was not detected in these samples, except for very low amounts in the sample representing the years from 1997 to 2000. Detection of low amounts of the 15ADON genotype in these historical samples and the relatively high amounts of 15ADON genotype in 2003 and following years correspond well with the occurrence of F. graminearum and indicates that the 15ADON genotype was introduced along with F. graminearum around 2000. The amounts of the 3ADON and 15ADON genotypes correlated well with the total amount of DON whereas the amounts of NIV genotype correlated well with the amount of NIV in wheat and triticale but not in barley where the results indicate that Fusarium poae may also contribute to the NIV content.

Disease Impact on Wheat Yield Potential and Prospects of Genetic Control

Wheat is grown worldwide in diverse geographical regions, environments, and production systems. Although many diseases and pests are known to reduce grain yield potential and quality, the three rusts and powdery mildew fungi have historically caused major crop losses and continue to remain economically important despite the widespread use of host resistance and fungicides. The evolution and fast spread of virulent and more aggressive race lineages of rust fungi have only worsened the situation. Fusarium head blight, leaf spotting diseases, and, more recently, wheat blast (in South America and Bangladesh) have become diseases of major importance in recent years largely because of intensive production systems, the expansion of conservation agriculture, undesirable crop rotations, or increased dependency on fungicides. High genetic diversity for race-specific and quantitative resistance is known for most diseases; their selection through phenotyping reinforced with molecular strategies offers great promise in achieving more durable resistance and enhancing global wheat productivity.

Synthesis and quantitation of six phenolic amides in Amaranthus spp.

Cinnamoylphenethylamines are phenolic amides in which cinnamic acid provides the acid moiety and phenethylamine the amine moiety. Single ion monitoring (SIM) in LC-MS was performed on amaranth leaf extracts. Masses corresponding to sets of regioisomers, including previously reported compounds, were examined. Six peaks were detected and their corresponding standards synthesized for a quantitative LC-MS/MS investigation of cinnamoylphenethylamines in amaranth. Four cinnamoylphenethylamines (caffeoyltyramine, feruloyldopamine, sinapoyltyramine, and p-coumaroyltyramine) are reported in the Amaranthaceae for the first time; also, one rare compound, feruloyl-4-O-methyldopamine, appeared to be quite common in the genus Amaranthus. Feruloyldopamine showed moderate antifungal activity toward an isolate of Fusarium culmorum. Our LC-MS approach, in conjunction with the straightforward synthesis, provides a simple, reliable way of quantitatively investigating cinnamoylphenethylamines in plants. Concentrations of cinnamoylphenethylamines vary widely: feruloyltyramine was present in quantities of 5.26 to 114.31 microg/g and feruloyldopamine in quantities of 0.16 to 10.27 microg/g, depending on the plant sample.

A transnational and holistic breeding approach is needed for sustainable wheat production in the Baltic Sea region

The Baltic Sea is one of the largest brackish water bodies in the world. Eutrophication is a major concern in the Baltic Sea due to the leakage of nutrients to the sea with agriculture being the primary source. Wheat (Triticum aestivum L.) is the most widely grown crop in the countries surrounding the Baltic Sea and thus promoting sustainable agriculture practices for wheat cultivation will have a major impact on reducing pollution in the Baltic Sea. This approach requires identifying and addressing key challenges for sustainable wheat production in the region. Implementing new technologies for climate-friendly breeding and digital farming across all surrounding countries should promote sustainable intensification of agriculture in the region. In this review, we highlight major challenges for wheat cultivation in the Baltic Sea region and discuss various solutions integrating transnational collaboration for pre-breeding and technology sharing to accelerate development of low input wheat cultivars with improved host plant resistance to pathogen and enhanced adaptability to the changing climate.

Erratum to: Resistance of wheat pathogen Zymoseptoria tritici to DMI and QoI fungicides in the Nordic-Baltic region - a status

Septoria tritici blotch (STB) caused by the ascomycete Zymoseptoria tritici (Z. tritici) is currently the most prevalent foliar disease in wheat in the Nordic-Baltic region. Fungicide availability in this region differs greatly and is generally more limited than in other European regions. Monitoring of fungicide sensitivity is an essential tool to survey changes in fungal populations in order to react and be able to adapt recommendations for fungicide use. In this study the authors give an overview of the current situation of 14α-demethylation inhibitor (DMI) and quinone outside inhibitor (QoI) sensitivity of Z. tritici from Scandinavia and the Baltic countries. A total of 985 isolates from the Nordic-Baltic region were investigated for EC50 of DMI epoxiconazole and prothioconazole. Fungicide sensitivity remains at a high level with values ranging from 0.07 to 0.48 mg L−1 for epoxiconazole and 1.17 to 9.47 mg L−1 for prothioconazole. Point mutation I381V in the DMI target gene CYP51 was dominant throughout the region, but mutations D134G, V136A/C and S524T were also detected in the population in 2014. Screening for inserts in the CYP51 promoter region revealed that a ~ 1000 bp insert is predominant in the entire region. Only a single isolate was found in Denmark, harbouring the 120 bp insert, known to reduce fungicide sensitivity. Two Danish isolates which had elevated resistance levels were associated with an enhanced efflux. Significant differences were found across the area for the presence of G143A, conferring QoI resistance. As there is only limited access to results from this area, these findings can serve as reference for future fungicide sensitivity investigations and for evaluation of changes in the Northern European Z. tritici population.

Control of seedling blight in winter wheat by seed treatments – impact on emergence, crop stand, yield and deoxynivalenol

Abstract Seedling blight caused by Fusarium spp. and Microdochium spp. is common on wheat grain, and severe attacks can lead to poor establishment of new crops. Several seed treatments using bitertanol, difenoconazole, triticonazole, maneb, fludioxonil or guazatine found to significantly control Fusarium seedling blight (Fusarium spp., Microdochium spp.) were improving germination and reducing seedling blight on roots and coleoptiles under field conditions in winter wheat. Some of the seed treatments were also shown to have an impact on soil-borne Fusarium in trials carried out under glasshouse conditions. In three field trials with 5–45% infected seeds no significant improvements on yields were seen from seed treatments, indicating that the Danish threshold of 15% attacked seeds is a conservative threshold. In two field trials including seed lots with more than 90% infected seeds, fludioxonil improved germination by approximately 100%, which led to an improved crop stand and yield increases in the range of 1.2–1.5 tonnes ha−1. Attacks of Fusarium head blight were relatively slight in the two trials and the content of deoxynivalenol was below the EU limits of 1250 ppb in the harvested grain. Even so, seed treatments with fludioxonil did not help reduce attacks of Fusarium head blight at GS 75 or content of deoxynivalenol in the harvested grain.

Spatiotemporal Variation and Networks in the Mycobiome of the Wheat Canopy

The phyllosphere is an important habitat for a diverse microbiome and an important entry point for many pathogens. Factors that shape the phyllosphere microbiome and also the co-existence among members and how they affect disease development are largely understudied. In this study we examined the wheat mycobiome by using metabarcoding of the fungal ITS1 region. Leaf samples were taken from four cultivars grown at two locations in Denmark. Samples were taken from the three uppermost leaves and at three growth stages to better understand spatiotemporal variation of the mycobiome. Analysis of read abundances showed that geographical location had a major effect in shaping the mycobiome in the total dataset, but also leaf position, growth stage and cultivar were important drivers of fungal communities. Cultivar was most important in explaining variation in older leaves whereas location better explained the variation in younger leaves, suggesting that communities are shaped over time by the leaf environment. Network analysis revealed negative co-existence between Zymoseptoria tritici and the yeasts Sporobolomyces, Dioszegia, and Cystofilobasidiaceae. The relative abundance of Z. tritici and the yeasts was relatively constant between individual samples, suggesting that fast growing fungi rapidly occupy empty space in the phyllosphere.